Method for identifying the optical network unit power off reason

ABSTRACT

A passive optical network (PON) component comprising a power switch, a detector configured to monitor the power switch, and a processor configured to receive an interrupt from the detector and transmit a message comprising a first indicator that the PON component has powered down, and a second indicator giving a reason for the power down. A passive optical network (PON) component comprising a processor configured to implement a method comprising receiving an interrupt message from a detector, determining a reason for the interrupt, and transmitting a dying gasp message comprising an indicator of the reason for the interrupt. A method comprising transmitting an alarm message comprising an optical network terminal (ONT) manual power off indicator that indicates the ONT is shutting down because a subscriber has turned off its power switch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/756,764 filed Apr. 8, 2010 by Michael Shaffer, et al., and titled“Method for Identifying the Optical Network Unit Power Off Reason,”which claims priority to U.S. Provisional Patent Application No.61/171,500 filed Apr. 22, 2009 by Michael R. Shaffer, et al., andentitled “A New Method for Identifying the Optical Network Unit PowerOff Reason,” both of which are incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

A passive optical network (PON) is one system for providing networkaccess over “the last mile.” The PON is a point-to-multi-point (P2MP)network comprised of an optical line terminal (OLT) at the centraloffice, an optical distribution network (ODN), and a plurality ofoptical network units (ONUs) at the customer premises. Some ONUs areconfigured to send a message indicating power loss at the ONU. Themessage does not include a reason for the power loss, and receiving apower loss message without a reason for the power loss can beproblematic for the recipient of the message.

SUMMARY

In an embodiment, the disclosure includes a passive optical network(PON) component comprising a power switch, a detector configured tomonitor the power switch, and a processor configured to receive aninterrupt from the detector and transmit a message comprising a firstindicator that the PON component has powered down, and a secondindicator giving a reason for the power down.

In another embodiment, the disclosure includes a passive optical network(PON) component comprising a processor configured to implement a methodcomprising receiving an interrupt message from a detector, determining areason for the interrupt, and transmitting a dying gasp messagecomprising an indicator of the reason for the interrupt.

In yet another embodiment, the disclosure includes a method comprisingtransmitting an alarm message comprising an optical network terminal(ONT) manual power off indicator that indicates the ONT is shutting downbecause a subscriber has turned off its power switch.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of an embodiment of a PON.

FIG. 2A is a schematic diagram of a first embodiment of an ONU withhardware centric power detection.

FIG. 2B is a schematic diagram of a second embodiment of an ONU withhardware centric power detection.

FIG. 2C is a schematic diagram of a third embodiment of an ONU withhardware centric power detection.

FIG. 3A is a schematic diagram of a first embodiment of an ONU withsoftware centric power detection.

FIG. 3B is a schematic diagram of a second embodiment of an ONU withsoftware centric power detection.

FIG. 3C is a schematic diagram of a third embodiment of an ONU withsoftware centric power detection.

FIG. 3D is a schematic diagram of a fourth embodiment of an ONU withsoftware centric power detection.

FIG. 3E is a schematic diagram of a fifth embodiment of an ONU withsoftware centric power detection.

FIG. 4 is a block diagram of an embodiment of a physical layeroperation, administration, and management (PLOAM) message.

FIG. 5 is a block diagram of an embodiment of ONT management and controlinterface (OMCI) alarm extensions.

FIG. 6 is a block diagram of an embedded operation, administration, andmanagement (OAM) message.

FIG. 7 is a flow chart of an embodiment of a method for indicating apower loss reason.

FIG. 8 is a schematic diagram of an embodiment of a general purposecomputer.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

One type of PON is a gigabit PON (GPON), which has been standardized byInternational Telecommunication Union (ITU) TelecommunicationStandardization Sector (ITU-T) G.984. GPON performs OAM functions usingthree channels: embedded OAM, PLOAM, and OMCI. Embedded OAM utilizesstructured overhead fields of downstream GPON transmission convergence(GTC) frames and upstream GTC bursts. Embedded OAM is defined by theITU-T G.984.3 standard, which is incorporated herein as if reproduced inits entirety. The PLOAM channel is a message-based OAM channel betweenthe OLT and the ONUs that supports the GTC layer management functions,including ONU activation, ONU management and control channelestablishment, encryption configuration, key management, and alarmsignaling. The PLOAM channel and message types are defined by the ITU-TG.984.3 standard. OMCI is a management channel between the OLT and theONUs that supports Ethernet, equipment, subscriber interface, andsubscriber feature management. OMCI is standardized in the ITU-T G.984.4standard, which is incorporated herein as if reproduced in its entirety.OMCI supports alarm reporting, and one type of alarm presently supportedby OMCI is a Dying Gasp alarm. The Dying Gasp alarm is reported to theOLT by an ONU when the ONU loses power. Dying Gasp may be reported viathe PLOAM channel and/or the OMCI channel.

Disclosed herein is a system and method for identifying an ONU power offreason. Some subscribers may power down an ONU when not in use toconserve electricity. A dying gasp message may be sent responsive to thesubscriber power down of the ONU. If the dying gasp message does notcontain a reason for the message, an OLT may interpret the power down asan area wide power disruption rather than an intentional subscriberaction. Thus, a dying gasp message may be sent to an OLT with a reasonfor the ONU power loss which may prevent erroneous action by the OLT orcentral office. The ONU may implement a hardware centric power switch, asoftware centric power switch, or both. The ONU may monitor the state ofthe power switch, input power level, or a battery power level, in orderto identify the cause for power loss at the ONU. After a power loss, theONU may send a message identifying the cause for the power loss beforepowering down.

FIG. 1 illustrates one embodiment of a PON 100 configured to implementthe concepts described herein. The PON 100 comprises an OLT 110, aplurality of ONUs 120, and an ODN 130, which may be coupled to the OLT110 and the ONUs 120. The PON 100 may be a communications network thatdoes not require any active components to distribute data between theOLT 110 and the ONUs 120. Instead, the PON 100 may use the passiveoptical components in the ODN 130 to distribute data between the OLT 110and the ONUs 120. The PON 100 may be Next Generation Access (NGA)system, such as ten gigabits per second (Gbps) GPONs (or XGPONs), whichmay have a downstream bandwidth of about ten Gbps and an upstreambandwidth of at least about 2.5 Gbps. Other examples of suitable PONs100 include the asynchronous transfer mode PON (APON) and the broadbandPON (BPON) defined by the ITU-T G.983 standard, the GPON defined by theITU-T G.984 standard, the Ethernet PON (EPON) defined by the Instituteof Electrical and Electronics Engineers (IEEE) 802.3ah standard, 10GEPON as defined by the IEEE 802.3av standard, and the wavelengthdivision multiplexed (WDM) PON (WPON), all of which are incorporatedherein by reference as if reproduced in their entirety.

In an embodiment, the OLT 110 may be any device that is configured tocommunicate with the ONUs 120 and another network (not shown).Specifically, the OLT 110 may act as an intermediary between the othernetwork and the ONUs 120. For instance, the OLT 110 may forward datareceived from the network to the ONUs 120, and forward data receivedfrom the ONUs 120 onto the other network. Although the specificconfiguration of the OLT 110 may vary depending on the type of PON 100,in an embodiment, the OLT 110 may comprise a transmitter and a receiver.When the other network is using a network protocol, such as Ethernet orSynchronous Optical Networking/Synchronous Digital Hierarchy(SONET/SDH), that is different from the PON protocol used in the PON100, the OLT 110 may comprise a converter that converts the networkprotocol into the PON protocol. The OLT 110 converter may also convertthe PON protocol into the network protocol. The OLT 110 may be typicallylocated at a central location, such as a central office, but may belocated at other locations as well.

In an embodiment, the ONUs 120 may be any devices that are configured tocommunicate with the OLT 110 and a customer or user (not shown).Specifically, the ONUs 120 may act as an intermediary between the OLT110 and the customer. For instance, the ONUs 120 may forward datareceived from the OLT 110 to the customer, and forward data receivedfrom the customer to the OLT 110. Although the specific configuration ofthe ONUs 120 may vary depending on the type of PON 100, in anembodiment, the ONUs 120 may comprise an optical transmitter configuredto send optical signals to the OLT 110 and an optical receiverconfigured to receive optical signals from the OLT 110. Additionally,the ONUs 120 may comprise a converter that converts the optical signalinto electrical signals for the customer, such as signals in theEthernet or asynchronous transfer mode (ATM) protocol, and a secondtransmitter and/or receiver that may send and/or receive the electricalsignals to a customer device. In some embodiments, ONUs 120 and opticalnetwork terminals (ONTs) are similar, and thus the terms are usedinterchangeably herein. The ONUs 120 may be typically located atdistributed locations, such as the customer premises, but may be locatedat other locations as well.

In an embodiment, the ODN 130 may be a data distribution system, whichmay comprise optical fiber cables, couplers, splitters, distributors,and/or other equipment. In an embodiment, the optical fiber cables,couplers, splitters, distributors, and/or other equipment may be passiveoptical components. Specifically, the optical fiber cables, couplers,splitters, distributors, and/or other equipment may be components thatdo not require any power to distribute data signals between the OLT 110and the ONUs 120. Alternatively, the ODN 130 may comprise one or aplurality of active components, such as optical amplifiers. The ODN 130may typically extend from the OLT 110 to the ONUs 120 in a branchingconfiguration as shown in FIG. 1, but may be alternatively configured inany other point-to-multi-point (P2MP) configuration.

In an embodiment, the OLT 110 and/or the ONUs 120 may comprise a dataframer, which may be coupled to the transmitter and/or the receiver. Thedata framer may be any device configured to process the data between theOLT 110 and the ONUs 120 by framing the data into frames or obtainingthe data from the frames according to a PON protocol, such as IEEE802.3ah and/or 802.3av. The data framer may be hardware, such as aprocessor, comprising electronic or logic circuitry, which may bedesigned for such purpose. Alternatively, the data framer may besoftware or firmware, which may be programmed for such purpose.Specifically, the data framer may be configured to generate media accesscontrol (MAC) control messages, which may be used to promote OAMfunctions in the PON 100. The data framer may be configured to generatedifferent control messages, for instance to implement different OAMfunctions according to different organizations or architectures. Forexample, the data framer may frame control data for different providers,customer networks, or standardization and/or regulatory organizations(e.g. IEEE, ITU-T, etc.) into a MAC control message.

FIG. 2A is a schematic diagram of a first embodiment of an ONU withhardware centric power detection 200. The ONU with hardware centricpower detection 200 may comprise an external power detector 203 coupledto an external power source 201 and a controller 205. The ONU withhardware centric power detection 200 may further comprise a hardwareswitch 202 coupled to a switch detector 204, an optional capacitor 208,and an internal circuit power module 207. The controller 205 may becoupled to the switch detector 204 and a host processor 206. The hostprocessor 206 may be coupled to the internal circuit power module 207and a gigabit media access controller (GMAC) (not shown). The internalcircuit power module 207 may be coupled to other functional modules notshown in the schematic diagram. The internal circuit power module 207may provide power for all of the modules in the ONU with hardwarecentric power detection 200.

The switch detector 204 may be configured to monitor and detect theposition of the hardware switch 202, e.g. on or off. If the hardwareswitch 202 is moved to the off position, the switch detector 204 maydetect the position of the switch and send an indicator to thecontroller 205. The indicator may notify the controller 205 of theposition of the hardware switch 202. The controller 205 may store theoccurrence of the hardware switch 202 changing to off. The controller205 may also store the time of the change and other relevant datarelated to the hardware switch 202 being changed to the off position.Upon receiving the indicator from the switch detector 204, thecontroller 205 may notify the host processor 206 of the change. Thenotification may be in the form of an interrupt sent to the hostprocessor 206. Upon receiving the interrupt, the host processor 206 mayuse system software to generate and transmit an ONU manual power offmessage comprising a reason for power loss indicator, e.g. ONU switchedoff. The generation and transmission of the ONU manual power off messagemay be performed by hardware and/or software available on the ONU withhardware centric power detection 200. The ONU manual power off messagemay be transmitted to an OLT at a central office. The central office orthe OLT may take actions based upon the reason for power loss containedin the ONU manual power off message.

The external power detector 203 may be configured to monitor and measurethe power level received from the external power source 201. If thepower level received from the external power source 201 drops below apredefined level, e.g. the level necessary for operation of the ONU withhardware centric power detection 200, the external power detector 203may alert the controller 205. Upon receiving the alert from the externalpower detector 203, the controller 205 may notify the host processor 206of the alert. The notification may be in the form of an interrupt sentto the host processor 206. The host processor 206 may then transmit amessage comprising the power loss reason to an OLT connected to the ONUwith hardware centric power detection 200, e.g. power loss due toexternal power source 201 failure.

The amount of time available for the ONU with hardware centric powerdetection 200 to generate and transmit a message after power loss isdependant upon the capacity of the capacitor 208. A capacitor 208 may beselected based upon the predetermined power required to generate andtransmit the dying gasp reports. The ONU with hardware centric powerdetection 200 may determine the power loss reason by indicators receivedat the controller 205. If the controller receives a first indicator fromthe switch detector 204 and a subsequent indicator from the externalpower detector 203, the ONU with hardware centric power detection 200may determine that the power switch has been formally shut off. If thecontroller only receives an indicator from the external power detector203, the ONU with hardware centric power detection 200 may determinethat power has been abnormally lost.

FIG. 2B is a schematic diagram of a second embodiment of an ONU withhardware centric power detection 230. The ONU with hardware centricpower detection 230 may be configured and function substantially similarto the ONU with hardware centric power detection 200. However, the ONUwith hardware centric power detection 230 comprises a controller/hostprocessor module 209. The controller/host processor module 209 maycombine the functionality of the controller 205 and the host processor206 into a single module. Combining modules into a single module mayreduce cost and size of the ONU with hardware centric power detection230. The functionality of other modules may also be combined into othersingle modules, e.g. to reduce cost, power consumption, size, and otherimprovements to the various embodiments disclosed herein.

FIG. 2C is a schematic diagram of a third embodiment of an ONU withhardware centric power detection 260. The ONU with hardware centricpower detection 260 may be substantially similar to the ONU withhardware centric power detection 200, however the ONU with hardwarecentric power detection 260 further comprises an external battery 211,and battery power detector 210. The external battery 211 may allow theONU with hardware centric power detection 260 to continue to function ifexternal power 201 is lost. The functionality of ONU with hardwarecentric power detection 260 remains substantially similar to that of theONU with hardware centric power detection 200. The battery powerdetector 210 monitors the power output from the external battery 211. Ifthe power level received from the external battery 211 drops below apredefined level, e.g. the level necessary for operation of the ONU withhardware centric power detection 260, the battery power detector 210 mayalert the controller 205. Upon receiving the alert from the batterypower detector 210, the controller 205 may notify the host processor 206of the alert. The notification may be in the form of an interrupt sentto the host processor 206. The host processor 206 may then transmit amessage comprising the power loss reason to an OLT connected to the ONUwith hardware centric power detection 260, e.g. power loss due toexternal battery 211 failure.

FIG. 3A is a schematic diagram of a first embodiment of an ONU withsoftware centric power detection 300. The ONU with software centricpower detection 300 may comprise an external power detector 305 coupledto an external power source 301, and a controller 306. The ONU withsoftware centric power detection 300 may further comprise a softwareswitch 303 coupled to a switch detector 304. The controller 306 may becoupled to the switch detector 304 and a host processor 307. The hostprocessor 307 may be coupled to an internal circuit power module 308 anda GMAC (not shown). The internal circuit power module 308 may be coupledto an optional capacitor 309, a hardware switch 302, and otherfunctional modules not shown in the schematic diagram.

The switch detector 304 may be configured to monitor and detect thestate of the software switch 303, e.g. on or off. If the software switch303 is changed to the off state, the switch detector 304 may detect thestate of the software switch 303 and send an indicator to the controller306 to notify the controller 306 of the state of the software switch303. The state of the software switch 303 may have changed to off,however power may still be applied to the ONU with software centricpower detection 300. The controller 306 may store the occurrence of thesoftware switch 303 state changing to off. The controller 306 may alsostore the time of the state change and other relevant data related tothe software switch 303 state being changed to the off position. Uponreceiving the indicator from the switch detector 304, the controller 306may notify the host processor 307 of the state of the software switch303. The notification may be in the form of an interrupt sent to thehost processor 307. Upon receiving the interrupt, the host processor 307may use system software to generate and transmit an ONU manual power offmessage comprising a reason for power loss indicator, e.g. ONU switchedoff. The generation and transmission of the ONU manual power off messagemay be performed by hardware and/or software available on the ONU withsoftware centric power detection 300. The ONU manual power off messagemay be transmitted to an OLT at a central office for tracking purposes.Upon transmitting the ONU manual power off message, the system softwaremay send an indicator to the controller 306 indicating that it is safeto power down. The controller 306 may then power down the ONU withsoftware centric power detection 300. In some embodiments, the systemsoftware may store any critical data in non-volatile memory prior tosending the power down indicator to the controller 306.

The external power detector 305 may be configured to monitor and measurethe power level received from the external power source 301. If thepower level received from the external power source 301 drops below apredefined level, e.g. the level necessary for operation of the ONU withsoftware centric power detection 300, the external power detector 305may alert the controller 306. Upon receiving the alert from the externalpower detector 305, the controller 306 may notify the host processor 307of the alert. The notification may be in the form of an interrupt sentto the host processor 307. The host processor 307 may then transmit apower loss message comprising the power loss reason to an OLT connectedto the ONU with software centric power detection 300, e.g. power lossdue to external power source 301 failure.

In the case of power loss at the external power source 301, the amountof time available for the ONU with software centric power detection 300to generate and transmit the power loss message is dependant upon thecapacity of the capacitor 309. A capacitor 309 may be selected basedupon the predetermined power required to generate and transmit the powerloss message. The ONU with software centric power detection 300 maydetermine the power loss reason by indicators received at the controller306. If the controller receives an indicator from the switch detector304, the ONU with software centric power detection 300 may determinethat the software power switch 303 has been formally shut off. If thecontroller receives an indicator from the external power detector 305,the ONU with software centric power detection 300 may determine thatpower has been abnormally lost.

FIG. 3B is a schematic diagram of a second embodiment of an ONU withsoftware centric power detection 320. The ONU with software centricpower detection 320 may be configured and function substantially similarto the ONU with software centric power detection 300. Thefunctionalities of the switch detector 304 and the external powerdetector 305 have been combined into a single module: detector 310.Detector 310 may be coupled to a software switch 303, an external powersource 301, and a controller 306. The detector 310 may serve as asubstitute for the switch detector 304 and the external power detector305 in any of the embodiments disclosed herein. Combining modules into asingle module may reduce cost and size of the ONU with software centricpower detection 320. The functionality of other modules may also becombined into other single modules, e.g. to reduce cost, powerconsumption, size, and other improvements to the various embodimentsdisclosed herein.

FIG. 3C is a schematic diagram of a third embodiment of an ONU withsoftware centric power detection 340. The ONU with software centricpower detection 340 may be configured and function substantially similarto the ONU with software centric power detection 300. In thisembodiment, the functionality of the switch detector 304, the externalpower detector 305, and the controller 306 may be combined into a singlemodule, detector/controller 311. The detector/controller 311 may becoupled to the host processor 307, the soft switch 303, and the externalpower source 301. As described above, combining modules into a singlemodule may reduce cost and size of the ONU with software centric powerdetection 340.

FIG. 3D is a schematic diagram of a fourth embodiment of an ONU withsoftware centric power detection 360. The ONU with software centricpower detection 360 may be configured and function substantially similarto the ONU with software centric power detection 300. Thefunctionalities of the switch detector 304 and external power detector305 have been combined into a single module, detector 310. Thefunctionalities of the host processor 307 and controller 306 have beencombined into a single module, controller/host processor 312. Detector310 may be coupled to the software switch 303, the external power source301, and the controller/host processor 312. The controller/hostprocessor 312 may be coupled to the internal circuit powering module 308and the GMAC. As described above, combining modules into a single modulemay reduce cost and size of the ONU with software centric powerdetection 360.

FIG. 3E is a schematic diagram of a fifth embodiment of an ONU withsoftware centric power detection 380. The ONU with software centricpower detection 380 may be configured substantially similar to the ONUwith hardware centric power detection 300. The ONU with software centricpower detection 380 further comprises an external battery 313, andbattery power detector 314. The external battery 313 may allow the ONUwith software centric power detection 380 to continue to function ifexternal power 301 is lost. The functionality of the ONU with softwarecentric power detection 380 remains substantially similar to that of theONU with software centric power detection 300. The battery powerdetector 314 monitors the power output from the external battery 313. Ifthe power level received from the external battery 313 drops below apredefined level, e.g. the level necessary for operation of the ONU withsoftware centric power detection 380, the battery power detector 314 mayalert the controller 306. Upon receiving the alert from the batterypower detector 314, the controller 306 may notify the host processor 307of the alert. The notification may be in the form of an interrupt sentto the host processor 307. The host processor 307 may then transmit amessage comprising the power loss reason to an OLT connected to the ONUwith software centric power detection 380, e.g. power loss due toexternal battery 313 failure. The external battery 313 and externalbattery power detector 314 may be added to any of the embodimentsdisclosed herein to provide backup power in the case of external power301 loss.

FIG. 4 is a block diagram of an embodiment of a PLOAM message 400, whichmay be used in conjunction with existing PLOAM alarm messages. PLOAMmessage 400 may be configured as a dying gasp message. The PLOAM message400 may comprise 12 octets. The first octet 410 may comprise anONU-identifier (ID). The ONU-ID may indicate the ONU that is sending thedying gasp message to an OLT. The second octet 420 may comprise amessage identification corresponding to a dying gasp message, e.g.‘00000011’. The third octet 430 may comprise a reason indicator. Thereason indicator may indicate to the OLT receiving the message thereason for the dying gasp message. A value of ‘00000001’ in the thirdoctet 430 may indicate that the power switch at the ONU was formallyturned off. A value of ‘00000010’ in the third octet 430 may indicatethat the external power at the ONU is abnormally off. A value of‘00000100’ in the third octet 430 may indicate that there is an internalcircuit fault at the ONU. The fourth through twelfth octets 440 may bereserved for future use. While several reason indicators are describedherein, other reason indicators may be used by the ONU to transmit areason for power loss at the ONU over the PLOAM channel.

FIG. 5 is a block diagram of an embodiment of OMCI alarm extensions 500,which may be used in conjunction with existing OMCI alarm messages. TheOMCI alarm extensions 500 may comprise new OMCI alarms indicating thecause of power loss at an ONT. OMCI alarm 7 510 may be a dying gaspalarm that indicates the ONT is powering off immediately due to loss ofpower to the ONT itself, rather than being turned off manually. Thisalarm may be sent in conjunction with the powering alarm if a backupunit cannot supply power and the ONT is shutting down. OMCI alarm 12 520may be an ONT manual power off alarm used to indicate that ONT isshutting down because a subscriber (e.g. a user) has turned off theONT's power switch. OMCI alarm 13 530 may be a dying gasp caused byexternal power loss message used to indicate that the ONT is poweringoff because of an external power loss. OMCI alarm 14 540 may be a dyinggasp caused by a circuit fault message used to indicate that the ONT ispowering off because of an internal circuit fault. While several OMCIalarms are described herein, other OMCI alarms may be used by the ONT totransmit a reason for power loss at the ONT over the OMCI channel.

FIG. 6 is a block diagram of an embedded OAM message 600, which may beused in conjunction with existing embedded OAM alarm messages. Theembedded OAM message 600 may comprise 8 bits. The embedded OAM message600 may correspond to the indication (Ind) field contained in thestructured overhead of upstream GTC frames. Bit seven 610 may be used toindicate if a PLOAM is waiting for the OLT. If bit seven 610 is set toone, then a PLOAM message may be waiting. If bit seven 610 is set tozero, then a PLOAM message may not be waiting. Bit six 620 may be usedto indicate the status of forward error correction (FEC). If bit six 620is set to one then FEC is on. If bit six 620 is set to zero, then FEC isoff. Bit five 630 may contain the remote defect indication (RDI) status.If bit five 630 is set to one, then a remote defect is present. If bitfive 630 is set to zero, then a remote defect is not present. Bit four640 may be reserved, and may be ignored by the OLT. Bits three throughone 650 may be used as a reason indicator. If bits three though one 650contain the sequence ‘001’, then the power switch at the ONU may havebee formally shut off. If bits three though one 650 contain the sequence‘010’, then the external power source at the ONU may be abnormally off.If bits three though one 650 contain the sequence ‘100’, then there maybe an internal circuit fault at the ONU. Bit zero 660 may be reservedfor future use. While several bit sequences for bits three through one650 are described herein, other bit sequences for bits three through one650 may be used by the ONU to transmit a reason for power loss at theONU over the embedded OAM channel.

FIG. 7 is a flow chart of an embodiment of a method for indicating apower loss reason 700. The method 700 starts at block 720, an ONU maymonitor its power switch and/or external power source. The monitoringmay be accomplished by a single module or a plurality of modules withinthe ONU. The external power source may be monitored for output powerlevel. The power switch may be monitored for the current position, e.g.on or off. The method continues at block 730 when the ONU may detect achange of the power switch, or power loss at the external power supply.At block 740, the ONU may send a message indicating the power lossreason to an OLT or some other upstream monitoring device. The messagemay be one or more of a PLOAM message, an embedded OAM message, or anOMCI message. The ONU may send the message via one, two, or three of aPLOAM channel, an embedded OAM channel, or an OMCI channel.

The network components described above may be implemented on anygeneral-purpose network component, such as a computer or networkcomponent with sufficient processing power, memory resources, andnetwork throughput capability to handle the necessary workload placedupon it. FIG. 8 illustrates a typical, general-purpose network component800 suitable for implementing one or more embodiments of the componentsdisclosed herein. The network component 800 includes a processor 802(which may be referred to as a central processor unit or CPU) that is incommunication with memory devices including secondary storage 804, readonly memory (ROM) 806, random access memory (RAM) 808, input/output(I/O) devices 810, and network connectivity devices 812. The processor802 may be implemented as one or more CPU chips, or may be part of oneor more application specific integrated circuits (ASICs).

The secondary storage 804 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 808 is not large enough tohold all working data. Secondary storage 804 may be used to storeprograms that are loaded into RAM 808 when such programs are selectedfor execution. The ROM 806 is used to store instructions and perhapsdata that are read during program execution. ROM 806 is a non-volatilememory device that typically has a small memory capacity relative to thelarger memory capacity of secondary storage 804. The RAM 808 is used tostore volatile data and perhaps to store instructions. Access to bothROM 806 and RAM 808 is typically faster than to secondary storage 804.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, R_(l), and an upperlimit, R_(u), is disclosed, any number falling within the range isspecifically disclosed. In particular, the following numbers within therange are specifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k isa variable ranging from 1 percent to 100 percent with a 1 percentincrement, e.g., k is 1 percent, 2 percent, 3 percent, 4 percent, 5percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent,96 percent, 97 percent, 98 percent, 99 percent, or 100 percent.Moreover, any numerical range defined by two R numbers as defined in theabove is also specifically disclosed. Use of the term “optionally” withrespect to any element of a claim means that the element is required, oralternatively, the element is not required, both alternatives beingwithin the scope of the claim. Use of broader terms such as comprises,includes, and having should be understood to provide support fornarrower terms such as consisting of, consisting essentially of, andcomprised substantially of. Accordingly, the scope of protection is notlimited by the description set out above but is defined by the claimsthat follow, that scope including all equivalents of the subject matterof the claims. Each and every claim is incorporated as furtherdisclosure into the specification and the claims are embodiment(s) ofthe present disclosure. The discussion of a reference in the disclosureis not an admission that it is prior art, especially any reference thathas a publication date after the priority date of this application. Thedisclosure of all patents, patent applications, and publications citedin the disclosure are hereby incorporated by reference, to the extentthat they provide exemplary, procedural, or other details supplementaryto the disclosure.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method comprising: detecting that an opticalnetwork terminal (ONT) meets one of a plurality of alarm conditionsrelative to power that are configured with respective alarm flags thatindicate alarm reasons in ONT management and control interface (OMCI)alarm messages; and transmitting, in response to the detecting, an OMCIalarm message with a corresponding alarm flag that indicates an alarmreason from the ONT, wherein the respective alarm flags comprise a firstalarm flag that indicate the ONT is shutting down because a subscriberhas turned off its power, wherein the first alarm flag corresponds to afirst alarm condition of the plurality of alarm conditions relative topower, wherein the respective alarm flags comprise a second alarm flagthat indicates the ONT is shutting down due to loss of power to the ONT,and wherein the second alarm flag corresponds to a second alarmcondition of the plurality of alarm conditions.
 2. The method of claim1, wherein the first alarm flag is alarm number
 12. 3. The method ofclaim 2, wherein the second alarm flag is alarm number
 7. 4. The methodof claim 1, wherein the OMCI alarm message complies with InternationalTelecommunication Union Telecommunication Standardization Sector (ITU-T)G.984.4.
 5. An apparatus comprising: a non-transitory medium that storescomputer executable instructions; and a processor that executes thecomputer executable instructions to cause the apparatus to perform thefollowing: detect that an optical network terminal (ONT) meets one of aplurality of alarm conditions relative to power that are configured withrespective alarm flags that indicate alarm reasons in ONT management andcontrol interface (OMCI) alarm messages; and transmit, in response tothe detecting, an OMCI alarm message with a corresponding alarm flagthat indicates an alarm reason from the ONT, wherein the respectivealarm flags comprise a first alarm flag that indicates the ONT isshutting down because a subscriber has turned off its power, wherein thefirst alarm flag corresponds to a first alarm condition of the pluralityof alarm conditions relative to power, wherein the re alarm rise asecond alarm a that ONT is shutting down due to loss of power to theONT, and wherein the second alarm flag corresponds to a second alarmcondition of the plurality of alarm conditions.
 6. The apparatus ofclaim 5, wherein the first alarm flag is alarm number
 12. 7. Theapparatus of claim 6, wherein the second alarm flag is alarm number 7.8. The apparatus of claim 5, wherein the apparatus is the ONT.
 9. Theapparatus of claim 5, wherein the OMCI alarm message complies withInternational Telecommunication Union Telecommunication StandardizationSector (ITU-T) G.984.4.
 10. A passive optical network (PON) componentcomprising: a processor configured to: receive an interrupt message froma detector; and determine whether a reason for the interrupt is a powerswitch is switched to off, external power is abnormally off, or aninternal circuit has a fault; and a controller configured to: store anoccurrence of the interrupt; and store a time of the interrupt; and atransmitter coupled to the processor and configured to transmit a dyinggasp message comprising an indicator of the reason for the interrupt.11. The PON component of claim 10, wherein the dying gasp message is aphysical layer operation, administration and management (PLOAM) messageand is transmitted on a PLOAM channel.
 12. The PON component of claim11, wherein the indicator is located in a third octet of the PLOAMmessage.
 13. The PON component of claim 11, wherein the processor isfurther configured to transmit a second dying gasp message comprisingthe indicator, and wherein the second dying gasp message is an embeddedoperation, administration and management (OAM) message and istransmitted on an embedded OAM channel.
 14. The PON component of claim13, wherein the indicator is located in bits one, two, and three of anindication (Ind) field contained in an overhead of an upstream gigabitpassive optical network transmission convergence (GTC) frame.
 15. ThePON component of claim 13, wherein the processor is further configuredto transmit a third dying gasp message comprising the indicator, andwherein the third dying gasp message is an optical network terminalmanagement and control interface (OMCI) message and is transmitted on anOMCI channel.
 16. The PON component of claim 15, wherein the indicatoris an alarm flag in the OMCI message.
 17. The PON component of claim 10,wherein the interrupt indicates that the reason for the interrupt is oneof: the power switch is switched to off, the external power isabnormally off, or the internal circuit has the fault.
 18. The PONcomponent of claim 10, wherein the detector is an external powerdetector and is configured to generate the interrupt message based onmonitoring the external power.
 19. The PON component of claim 10,wherein the detector is a switch on/off detector and is configured togenerate the interrupt message based on monitoring a hardware switch.20. The PON component of claim 10, further comprising an external powercoupled to the detector, wherein the detector is configured to generatethe interrupt message based on monitoring the external power.
 21. ThePON component of claim 10, further comprising a hardware switch coupledto the detector, wherein the detector is configured to generate theinterrupt message based on monitoring the hardware switch.
 22. The PONcomponent of claim 10, wherein the dying gasp message complies withInternational Telecommunication Union Telecommunication StandardizationSector (ITU-T) G.984.4.